Where's the issue(s) causing these

[TinCanAlley]

So I got the thermistor replaced and it does a better job degaussing, but I'll have to cycle it a number times to see if it's enough.

I started running though some test patterns and noticed two things disturbing. I'm attaching some pictures. In the first pic you can see the upper left dip down. I have not idea how to fix this and it's not noted in the service manual.

In the second and third pics, there is some issue with displaying the white lines of the grid. I know the convergence is a bit off, but this doesn't seem tied to that. There are color bands to the left and right of the lines and they appear as though their in motion (from bottom to top). Again, the service manual makes not mention of such and issue.

I really want to get the set up and going, but every time I turn around there's another issue or two to address.

Thanks for all the help.

[N2IXK]

If you disconnect the degaussing coil, does the problem go away?

If the coil current never shuts down completely due to an improper thermistor value, wavering color patterns will show on the screen.

[TinCanAlley]

Originally Posted by N2IXK

If you disconnect the degaussing coil, does the problem go away?

If the coil current never shuts down completely due to an improper thermistor value, wavering color patterns will show on the screen.

I disconnected the degauss coil and it still exists. I forgot to note that the white lines on the screen appear to be "flickering." Kind of like the refresh rate is wrong. That could just be and older set displaying a modern pattern.

The service manual says something about an APC adjustment. IT says to adjust for minimum movement of color bars.

I got this set used and it is obvious that someone messed with quite a few of the controls. They might have messed with some of the less common ones as well.

[andy]

...

[TinCanAlley]

Originally Posted by andy

The first issue is some geometric distortion. If the set has a pincushion phase adjustment, it should help, but many sets don't have an adjustment.

The second issue is caused by high frequency luma information getting decoded as color. It's unavoidable on a TV without a comb filter to separate the chroma and luma from each other. You can reduce it by rolling off the video bandwidth, but you will lose fine detail.

The real question is how does it look when viewing normal video? These older sets almost always look shockingly bad when viewing certain test patterns. It's just a fact of the limited technology available at the time. Old TVs are fun to restore, but don't expect to get the same picture quality as a modern set with a digital comb filter.

Tomorrow is the day to redo the static convergence, purity and dynamic convergence. The internal degauss wasn't strong enough and now it looks like crap after being moved. My brother is bringing is degauss coil and we'll use that before redoing the purity while in the position it will be viewed. After that I should be able to do the convergence (had to buy an alignment tool set as some of the convergence controls are coils that I didn't have a tool that fit).

I've been trying to compare it to my 19JC55Z chassis CC2. I know it's a couple years newer, but the picture is just about perfect (minor convergence and slightly tilted image). If I can get this one looking like that, I'll be happy.

[TinCanAlley]

Originally Posted by andy

The first issue is some geometric distortion. If the set has a pincushion phase adjustment, it should help, but many sets don't have an adjustment.

The second issue is caused by high frequency luma information getting decoded as color. It's unavoidable on a TV without a comb filter to separate the chroma and luma from each other. You can reduce it by rolling off the video bandwidth, but you will lose fine detail.

The real question is how does it look when viewing normal video? These older sets almost always look shockingly bad when viewing certain test patterns. It's just a fact of the limited technology available at the time. Old TVs are fun to restore, but don't expect to get the same picture quality as a modern set with a digital comb filter.

Forgot...the set does have a pin cushion adjustment. It's on the bottom of the chassis, so is it okay to adjust it while the set is on its side?

[andy]

...

[TinCanAlley]

Originally Posted by andy

Pincushion shouldn't be affected by having the set on its side, but you'll have to ignore the purity.

Found the pincushion coil on the bottom side of the chassis. They put a hole on the bottom of the cover, but it's too small to get the tool thorough. Go figure.

Anyway, I managed to get the drooping upper left back to pretty much level with the right side. Too much adjustment made the right side change and same with the bottom. It was a compromise, but it looks so much better.

Thanks!

[colorfixer]

Does the fringing dissipate when the color level is turned down? This looks a lot like a pattern generator that is keeping the chroma burst on during a monochrome pattern.

Modern sets have a color killer circuit that prevents this:
http://en.wikipedia.org/wiki/Color_killer

The explanation here describes how Israel held back on color tv and what viewers did to counter it. Never underestimate the determined viewer.

[TinCanAlley]

Originally Posted by colorfixer

Does the fringing dissipate when the color level is turned down? This looks a lot like a pattern generator that is keeping the chroma burst on during a monochrome pattern.

Modern sets have a color killer circuit that prevents this:
http://en.wikipedia.org/wiki/Color_killer

The explanation here describes how Israel held back on color tv and what viewers did to counter it. Never underestimate the determined viewer.

Those are calibration patterns from the Video Essentials DVD. They effect is also seen with all overlay video (onscreen displays, etc.). It is also showing, but much more subtle, in some video scenes.

I adjusted the color killer as described in the SM. It said to turn to static channel, adjust control until there is color in the static and then back it off until there are no signs of color. I did this once and noticed that there were occasional bursts of color, so I backed it off a bit more until that no longer happened. Should I try to back it off a bit more?

[andy]

...

[Username1]

"" That's not true, all color TVs since the CT-100 have had a color killer circuit. They aren't always completely accurate, or adjusted correctly, but that TV definitely has one. If it didn't, B/W broadcasts would be full of colored snow. That pattern generator probably keeps the color burst active all the time. Actually, based on the appearance, I'm guessing he's using a DVD player, or maybe a PC as the pattern generator. ""

Yup I vote for this too ! ! !

[wa2ise]

Originally Posted by andy

The second issue is caused by high frequency luma information getting decoded as color. It's unavoidable on a TV without a comb filter to separate the chroma and luma from each other. You can reduce it by rolling off the video bandwidth, but you will lose fine detail.

It's possible to reduce this crosstalk, if you have a source that provides "S-video" aka luma and chroma on separate wires. Before the luma and chroma are merged to create composite video, low pass or notch filter the luma to remove luma above about 2.5MHz. Anything above that will end up as crosstalk into the chroma demodulator, and isn't seen as luma on a set not using a comb filter.

luma---> 3.58 notch filter----> to composite mixer

chroma---> 3.58 band pass filter---> to above composite mixer

And the composite then feeds an RF modulator.